The present invention relates to an IC socket which accommodates a BGA (ball grid array) package.
Conventionally, BGA packages in which a plurality of electrodes consisting of solder balls are lined up on the undersurface of the package have been used in order to facilitate soldering to a circuit board. When such BGA packages are used, soldering can be completed by placing the BGA package on the surface of the circuit board and heating the package.
In order to test the functions of ICs mounted on such BGA packages prior to final assembly, it is necessary to align the solder balls on the undersurface of the BGA and maintain the package in this state as testing occurs. Conventionally, IC sockets for BGA packages have been used for this purpose. FIG. 7 is a diagram which shows the schematic construction and problem points of a conventional IC socket for a BGA package.
As is shown in FIG. 7(A), numerous solder balls 11 are lined up on the undersurface of the BGA package 10. This BGA package 10 is placed on a package accommodating plate 20 (shown in FIG. 7(B)) which forms an IC socket that accommodates the BGA package 10. Solder ball receiving holes 21 are formed in this package accommodating plate 20 in positions corresponding to the solder balls 11 on the undersurface of the BGA package 10. As is shown in FIG. 7 (C), the BGA package 10 is placed on the package accommodating plate 20 so that the solder balls 11 on the undersurface of the BGA package 10 enter the solder ball receiving holes 21. The package accommodating plate 20 is driven upward relative to the IC socket main body (not shown in the figures) by means of coil springs 22. These coil springs 22 are compressed as a result of the BGA package 10 being pressed from above, so that the solder balls 11 contact pins (not shown in the figures) that are lined up on the IC socket main body. The pins that are lined up on the IC socket main body are also spring-driven upward. When the BGA package 10 is pushed from above, these pins are pressed by the solder balls 11 on the undersurface [of the BGA packaged 10], so that the pins move somewhat in the sinking direction. Thus, the solder balls 11 securely contact the pins, so that electrical continuity is established between the solder balls and pins, and therefore between the IC inside the BGA package and the test apparatus, thus allowing operational testing of the IC inside the BGA package to be performed.
When the BGA package 10 is placed on the package accommodating plate 20, the solder balls 11 inevitably tend to contact the edges of the solder ball receiving holes 21, so that small portions of the solder balls are scraped away during each testing cycle. Consequently, as is shown in FIG. 7(D), the solder debris 11xe2x80x2 created by this scraping accumulates at the edges of the solder ball receiving holes 21, thus impeding the mounting of the BGA package. This solder debris 11xe2x80x2 may also fall toward the IC socket main body, so that there is a danger that the movement of the pins will be hindered, thus reducing the long-term reliability of the IC socket.
In light of the above facts, it would be desirable to provide an IC socket for a BGA package which has high reliability and can withstand long-term use.
The IC socket for a BGA package provided by the present invention, which achieves the above-mentioned object. The IC socket accommodates a BGA package which has a plurality of electrodes consisting of solder balls lined up on its undersurface. The socket has a housing in which an accommodating part that accommodates the BGA package from above is formed. Electrode pins are lined up in the bottom portion of the above-mentioned accommodating part, such that the electrode pins contact the solder balls on the undersurface of the accommodated BGA package. Package receiving members are disposed so that these members protrude into the above-mentioned accommodating part from both sides of the accommodating part. The package receiving members have package receiving parts that receive the portions of the BGA package located in the vicinity of the opposite edges of the undersurface of the BGA package and pivot downward with the accommodating movement of the BGA package. The members are shaft-supported on the above-mentioned housing so that these package receiving members are free to pivot, and are spring-driven in the direction that lifts the BGA package received by the above-mentioned package receiving parts.
In the case of the IC socket for a BGA package that is provided by the present invention, only the electrode pins contact the solder balls. Accordingly, the chance of the solder balls being scraped is greatly reduced, so that high reliability is maintained even in the case of long-term use.